RP talk is a shortened term of the words role-play talk in which one has to type his actions in the middle of two asterisks and/or other symbols - since they are just meant to differentiate, and his normal speech without any other symbols whatsoever.

Example:
rp talk
*gaia saw two of her friends and gestured for them to come she smiles* Good morning everyone

*kisses milady's lips and pulls her closer* sorry, i can no longer control myself *pins milady to a wall*